I. Field of the Invention
This invention relates to feed supplements for ruminant animals and, more particularly, to buffers used for dairy cattle and other bovines.
II. Description of the Prior Art
It is well known that the milk yields, dry matter consumption and the health of lactating dairy cows suffer when the animals are fed acidotic rations (e.g. high starch rations) over a period of time. These rations, which contain a high level of concentrate (grains, supplements, etc.) and low fiber, reduce the secretion of saliva and the rumen liquor pH that is normally at almost the neutral level (6.0-6.5).
The variation of the rumen pH is principally attributable to increased ruminal fermentation leading to the production of organic acids (acetic acid, butyric acid, propionic acid, etc.). Moreover, the highly concentrated diet reduces the chewing and mastication time, thus reducing the production of alkaline saliva which normally assists in stabilizing the rumen pH since it contains natural buffers like bicarbonates.
The ruminal pH may be brought back to the natural level by feeding an alkaline material, such as sodium carbonate, sodium bicarbonate or sodium sesquicarbonate, to the animals and, when this is done, milk yields return to normal. It has been found to be particularly beneficial to combine one or more of these ingredients with magnesium oxide to prevent milk and fat depression attributable to a high concentrate ration.
Unfortunately, in order to affect rumen pH sufficiently, quite large amounts of alkaline materials of these kinds must be fed to the animals. For example, a cow having a high level of milk production can produce the equivalent of one to two kilograms of sodium bicarbonate in her saliva each day, which illustrates the type of quantities involved. Even though, in practice, such large quantities do not have to be served to the animals, even smaller amounts such as 300 to 400 grams of buffers are unappealing to the animals, particularly when magnesium oxide is present because this material seems to be particularly unpalatable to cattle. If attempts are made to make cattle "swallow" great quantities of magnesium oxide and buffers in this way, the animals usually refuse to eat the mineral and accompanying feedstuffs. Consequently, if the buffers are mixed with the regular feedstuffs, there may be a reduction in the consumption the feed, which can lead to obvious problems, and the animals may have difficulty adapting to the treated feedstuffs.
In order to overcome this problem, attempts have been made to make the buffer ingredients more appealing to the animals by pelletizing the ingredients with molasses, corn, by-products and flavors. Nevertheless, the animals almost have to be "force fed" to get them to accept the buffers in significant amounts. Even if the products are made to have an appealing smell, they still obviously retain an unacceptable taste for the animals. The buffers treated in this way are normally offered "top-dressed" on the ration or mixed in the concentrate and delivered in controlled quantities. Consequently, if the animals do not eat the buffers, they do not eat their normal ration.
Sometimes the buffers are offered on a free choice basis, e.g. loose in an auger or manger. However, because the buffers are unpalatable to a greater or lesser extent depending on individual preferences, many animals do not consume the required amounts. Moreover, since the buffers are highly hygroscopic, animal saliva and ambient humidity cause caking and the formation of clods, thus making the buffers unpalatable and unusable, and resulting in unacceptable losses of useful material.
It would therefore be highly desirable to produce a palatable free-choice block containing buffers as a convenient way to supply adequate amounts of these elements to dairy cattle or other bovines in order to prevent or alleviate acidosis attributable to high energy, low fiber diets or diets containing humid and fermented acid feeds. The advantage of free-choice blocks is that the blocks cause the buffering ingredients to dissolve on the animals' tongues, stimulating salivation and thus producing a double antacid effect: firstly by delivering the buffering agents, and secondly by promoting secretion of saliva, which itself contains natural buffers. Since the buffer blocks are offered free-choice, they are not force-fed to the animals, so there is no negative impact on the consumption of the feed rations. Moreover, when the buffers are presented in block form, the ingredients are consumed over a long period of time, allowing the buffers to stabilize the rumen pH all day long.
Furthermore, in solid block form, the problem of caking of powdered ingredients is avoided and the buffer is easier to use. Overconsumption of buffers is also prevented by self-regulation by the animals, based on the homeostatic system to maintain the blood pH and the whole system in a neutral environment and to maintain the acid-base balance. For example, an animal having a severe deficiency of sodium can experience an intense craving for salt and can manifest pica by licking and chewing various objects. The same is believed to be true of buffers, since animals experiencing severe deficiencies of buffers will tend to ingest soil containing grit as a physical conditioner. Since such severe deficiencies will lower the productivity of the animal, it is better to prevent this condition and to provide the necessary buffers in the form of a palatable block that will result in free-choice consumption of the proper amounts of buffer.
One way of producing such blocks is by the so-called poured block technique. Poured blocks are usually formed by mixing the buffer ingredients, and other materials such as vitamins, minerals and flavors, etc., with liquid ingredients such as molasses, pouring the resulting slurry or paste into a mold and then either heating the mixture to remove excess water or allowing it to dry or gel and harden over time.
A method of forming free choice buffer blocks is disclosed, for example, in U.S. Pat. No. 4,729,896 to Sawhill issued Mar.8, 1988. This is a typical example of the gelled or poured block technique in which feed solution, e.g. molasses in the form of a thin or thick syrup, in an amount of 30-95% by weight of the final mixture, is solidified or gelled by the addition of sodium carbonate/bicarbonate (8-25% by weight) and magnesium oxide (2-5% by weight). However, the resulting blocks contain a large proportion of molasses or other sugar solution and only small proportions of the buffer ingredients.
Canadian patent 1,126,568 to Skoch issued Jan. 29, 1982 also discloses a block containing a large amount (18-74% by weight) of molasses formed by molding and solidifying a liquid mixture.
Since these buffer blocks contain only relatively small amounts of buffer equivalent (e.g. 16% by weight in the case of the preferred Sawhill blocks), animals have to ingest large quantities of the block. To obtain the equivalent of 200 grams of bicarbonate/carbonate by day, animals will have to consume 1.25 kg of these blocks, which is a large amount for a block offered on a free choice basis and thus the blocks may not be able to deliver sufficient amounts of the buffers.
Poured or gelled blocks also suffer from the disadvantages that the method of preparation is slow and uneconomical and that the blocks are rather soft, but dry out over time and tend to crack.